Date Full Report Received


Date Abstract Report Received



Primary Investigator:

Direct fed microbials (DFM) have been investigated as a potential replacement for sub-therapeutic antibiotics in swine diets with mixed results being reported. Our results, found no overall significant effect of DFM or their mode of administration on growth rate. However, we also did not observe an effect of carbadox on overall growth rate, although ADG was improved during phase 3 when carbadox was added to the diet. A few small improvements in intestinal morphology and indicators of cellular migration and proliferation rate with in the gastrointestinal tract were observed when antibiotics were included in the diet. Adding DFM to the diet or administering DFM as a bolus at weaning followed by a diet containing DFM did return gut morphological measurements to a higher level than the negative control treated pigs which was not different from the antibiotic treated pigs. In summary, responses to DFM treatments in this experiment were relatively small. However, so was the response to in-feed antibiotics. Therefore, it is not surprising that a response to DFM was not observed. However, even with minimal performance responses there were indications that DFM and antibiotics may alter gut morphology and possibly the active transport rates of nutrients by the gastrointestinal tract. Therefore, more research is needed to further elucidate the mechanisms through which DFM function.